The present invention relates to an electronic apparatus with an azimuth meter having an azimuth sensor for electrically detecting the earth magnetism and a battery for driving respective drive units, which is capable of measuring an accurate azimuth and capable of being miniaturized, and relates to an azimuth measuring method in the electronic apparatus.
In recent years, there are some electronic apparatuses which are capable of measuring an azimuth easily. As one example of such the electronic apparatuses, an overall view of a digital electronic wrist watch with the azimuth meter which is on a market is shown in FIG. 12.
The digital electronic wrist watch 130 with an azimuth meter includes an azimuth measuring button 132 which is operated when an azimuth is measured, a liquid crystal display panel 131 having a magnetic north mark 134 for indicating the magnetic north and a 16 compass points display section 135 for displaying an azimuth of the 16 compass points which matches with a twelve o""clock direction of the electronic wrist watch 130, an azimuth sensor 133 for electrically measuring an azimuth from the earth magnetism, and an azimuth register ring 136 which can be rotated with respect to the liquid crystal display panel 131.
When the azimuth measuring button 132 is pushed, the magnetic north is measured by the azimuth sensor 133, and the magnetic north is indicated on the liquid crystal display panel 131 by the magnetic north mark 134 in about one second. Moreover, the direction of the twelve o""clock of the electronic wrist watch 130 (NNE in FIG. 12) is displayed on the 16 compass points display section 135. When the azimuth register ring 136 is rotated and the N (north azimuth) 136a is matched with the magnetic north mark 134, an azimuth can be grasped at will.
However, in the electronic apparatus with the azimuth meter having a battery and one or a plurality of drive units driven by the battery, a magnetic field generated from the battery and a driver such as a stepping motor disturbs the earth magnetism around the azimuth sensor, and thus it is difficult to measure the accurate azimuth.
In order to solve such a problem, the devised position for providing position of the battery is suggested, but the position of the battery is limited. Also since the battery is separated from the azimuth sensor as far as possible, a circuit substrate becomes larger. As a result, the electronic apparatus cannot be miniaturized.
Further, since a rotor made of a permanent magnet of the driver such as the stepping motor is rotated, a magnetic field changes complicatedly, and when a plurality of the stepping motors are provided, the magnetic field becomes more complicated so that the correction becomes difficult. As a result, an accurate azimuth cannot be measured. When indication of an azimuth is displayed on a liquid crystal display shown in FIG. 12, it is not necessary to provide a stepping motor for moving an azimuth needle. However, it is difficult to see the liquid crystal display due to a problem of a view angle.
It is an object of the present invention to provide an electronic apparatus with the azimuth meter having an azimuth sensor for electrically detecting the earth magnetism which is capable of measuring an accurate azimuth even if one or a plurality of magnetized member(s) for generating a magnetic field exist(s), and which is easy-to-watch and can be miniaturized by relieving a limit of a providing position of the magnetized member for generating strong magnetism such as a magnetized battery and stepping motor, and to provide an azimuth measuring method in the electronic apparatus with the azimuth meter.
In an electronic apparatus with an azimuth meter according to the present invention having an azimuth sensor for electrically detecting the earth magnetism, a magnetic screen for blocking off the azimuth sensor from a magnetic field is provided around a magnetized member provided in the electronic apparatus with an azimuth meter or between the magnetized member and the azimuth sensor, so that an accurate azimuth can be measured.
xe2x80x9cThe magnetized memberxe2x80x9d is a member which is easily magnetized by external magnetism as well as a member magnetized by external magnetism and a member having a magnet, and it includes a driver such as a motor having a battery and a magnet.
In addition, a limit of the providing position of the magnetized member can be relieved, and the electronic apparatus with an azimuth meter which is provided with an azimuth needle and is easily seen can be obtained.
In addition, an electronic apparatus with an azimuth meter according to the present invention, which includes an azimuth sensor for electrically detecting the earth magnetism and a driver having a rotor composed of a permanent magnet and a coil for driving the rotor, is provided with an azimuth sensor for measuring an azimuth when the driver rests, time detecting means for detecting the rotation starting time of the rotor, rotor magnetic field predicting means for predicting rest time of the rotor and an azimuth of a magnetic field generated from the rotor from a rotating starting signal detected by the time detecting means and a direction of a driving current flowing through the coil, and correcting means for correcting the measured azimuth according to the predicted result.
As a result, the correction can be made according to a change in a magnetic pole with the rotation of the rotor, and thus an accurate azimuth measured azimuth can be always obtained.
Further, in an azimuth measuring method of an electronic apparatus with an azimuth meter according to the present invention, the electronic apparatus including an azimuth sensor for electrically detecting the earth magnetism, a battery for driving respective drive units and a driver positioned in the drive units having a rotor made of a permanent magnet and a coil for driving the rotor, the azimuth measuring method, includes the steps of: measuring an azimuth by driving the azimuth sensor when the driver rests; predicting rest time of the rotor and a direction of a magnetic field generated from the rotor based on rotation starting time of the rotor and a direction of a driving current flowing through the coil; and correcting the measured azimuth according to the predicted result. As a result, the correction can be made according to a change of the magnetic pole with the rotation of the rotor, and an accurate azimuth measured azimuth can be always obtained.
In addition, an electronic apparatus with an azimuth meter according to the present invention, which has an azimuth sensor for electrically detecting the earth magnetism and a driver having a rotor composed of a permanent magnet and a coil for driving the rotor, is provided with the azimuth sensor measuring an azimuth when the driver rests; time detecting means for detecting rotation starting time of the rotor; predicting means for predicting rest time of the rotor from a rotation starting signal detected by the time detecting means; and correcting means for correcting the measured azimuth. As a result, an accurate azimuth measured azimuth can be always obtained.
Further, in an azimuth measuring method of an electronic apparatus with an azimuth meter according to the present invention, the electronic apparatus including an azimuth sensor for electrically detecting the earth magnetism, a battery for driving respective drive units and a driver positioned in the drive units having a rotor made of a permanent magnet and a coil for driving the rotor, the azimuth measuring method, includes the steps of: measuring an azimuth by driving the azimuth sensor when the driver rests; predicting rest time of the rotor based on rotation starting time of the rotor; and correcting the measured azimuth. As a result, an accurate azimuth measured azimuth can be always obtained.
In addition, an electronic watch with an azimuth meter according to the present invention, which has an azimuth sensor for electrically detecting the earth magnetism and a driver having a rotor composed of a permanent magnet and a coil for driving the rotor, is provided with the azimuth sensor measuring an azimuth when the driver tests; means for returning a time hand or a function hand driven by the driver to a predetermined position; and correcting means for correcting the measured azimuth. As a result, an accurate azimuth measured azimuth can be always obtained.
Further, in an azimuth measuring method of an electronic watch with an azimuth meter according to the present invention, the electronic apparatus including an azimuth sensor for electrically detecting the earth magnetism, a battery for driving respective drive units and a driver positioned in the drive units having a rotor made of a permanent magnet and a coil for driving the rotor, means for returning a time hand or function hand driven by the driver to a predetermined position is provided, and an azimuth is measured by driving the azimuth sensor when the driver rests so that the measured azimuth is corrected. As a result, an accurate azimuth measured azimuth can be always obtained.